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Retatrutide dosing

Also known as: LY3437943 · Reta · GLP-3 · GLP-3 RT

Updated Oct 23, 202674 sources

Every Retatrutide protocol on file, 18 in all, labelled by where each number came from. 5 have titration steps, each step is worked out in U-100 units for a 10 mg vial + 2 mL water.

Calculate with Retatrutide Retatrutide overview

Retatrutide dosing by goal

Grouped by goal. Each protocol shows the amount, how often, cycle and rest as the source states them, with every titration step.

Weight loss6

Weight loss, phase 3 trial schedule (TRIUMPH)

Amount: 2 to 12 mg
How often: Once weekly. Start at 2 mg, step up every 4 weeks to a target of 4, 9 or 12 mg, then hold.
Route: Subcutaneous injection
Cycle: 80 weeks in the trial

Who: Adults with obesity or overweight in the 80-week TRIUMPH phase 3 trials.

Timing: Any time of day. The trial allowed up to 2 permanent dose cuts for side effects that were hard to tolerate.

Weight loss, phase 3 step ladder as published by dosing guides

Amount: 2 to 12 mg
How often: Once weekly, 4 weeks at each step: 2, 4, 6, 9, then 12 mg and hold
Route: Subcutaneous injection

Who: Dosing guides describing the TRIUMPH ladder. Lilly confirms the 2 mg start and 4-week steps, not every rung.

Timing: If a dose is missed, guides following the trial protocol say take it within 5 days, otherwise skip it.

Titration steps for Weight loss, phase 3 step ladder as published by dosing guides
When	Dose	U-100 units (10 mg vial + 2 mL water)
Weeks 1 to 4	2 mg	40 units · 0.4 mL
Weeks 5 to 8	4 mg	80 units · 0.8 mL
Weeks 9 to 12	6 mg	120 units · 1.2 mL(2 draws)
Weeks 13 to 16	9 mg	180 units · 1.8 mL(2 draws)
Weeks 17 to 20	12 mg	240 units · 2.4 mL(3 draws)

Weight loss, phase 2 trial (48 weeks)

Amount: 1 to 12 mg
How often: Once weekly. Start at 2 or 4 mg, step up every 4 weeks to 4, 8 or 12 mg.
Route: Subcutaneous injection
Cycle: 48 weeks

Who: Adults with obesity in the phase 2 trial (338 people). One arm stayed at a fixed 1 mg.

Timing: Starting at 2 mg instead of 4 mg partly reduced stomach side effects and cost little weight loss: 16.3% vs 17.8% at 4 mg, 21.7% vs 23.9% at 8 mg, at 48 weeks.

Weight loss, common community start

Amount: 0.25 to 1 mg
How often: Once weekly, held a few weeks to judge tolerance before stepping up
Route: Subcutaneous injection

Who: Self-reported on r/Retatrutide and in community diaries. 1 mg weekly is the most common start in posts; some start at 0.25 to 0.6 mg. In one app's logs from 126 users, 1 to 2 mg per shot was most common. Not trial tested.

Weight loss, trial-style start (community)

Amount: 2 to 4 mg
How often: Once weekly: 2 mg for 4 weeks, then 4 mg
Route: Subcutaneous injection

Who: Community posters who copy the trial start instead of starting low.

Titration steps for Weight loss, trial-style start (community)
When	Dose	U-100 units (10 mg vial + 2 mL water)
Weeks 1 to 4	2 mg	40 units · 0.4 mL
Weeks 5 to 8	4 mg	80 units · 0.8 mL

Weight loss, small weekly steps (community)

Amount: 0.5 to 1.5 mg
How often: Once weekly, raised a little every 1 to 2 weeks
Route: Subcutaneous injection

Who: Community posters who climb in small steps, for example 1 to 1.2 to 1.5 mg, or 0.5 to 0.75 to 1 mg. One diary adds 0.5 mg every 2 weeks. Not trial tested.

Switching from tirzepatide2

Switching from tirzepatide (guide)

Amount: 1 to 1.5 mg
How often: Once weekly, starting at about 20 to 30% of the tirzepatide dose (5 mg tirzepatide becomes 1 to 1.5 mg)
Route: Subcutaneous injection

Who: A switching guide. No trial guidance exists for this switch.

Timing: First retatrutide shot on the next scheduled day, no washout. The guide cites 3 to 6 mg as a typical maintenance range.

Switching from tirzepatide (community)

Amount: 0.5 to 1 mg
How often: Once weekly, restarting low at 0.5 to 1 mg
Route: Subcutaneous injection

Who: Community posters switching from tirzepatide (Mounjaro or Zepbound).

Timing: Some wait 1 to 2 weeks after the last tirzepatide shot before starting.

Other protocols: injected10

Type 2 diabetes, phase 1b trial (12 weeks)

Amount: 0.5 to 12 mg
How often: Once weekly. Start between 0.5 and 3 mg, then ladders of 3 to 6 mg or 3, 6, 9 and 12 mg.
Route: Subcutaneous injection
Cycle: 12 weeks

Who: Adults with type 2 diabetes in a 12-week phase 1b trial.

Split dosing, twice weekly (community)

Amount: 0.5 to 1 mg
How often: Twice weekly: 0.5 mg for 2 weeks, 0.75 mg for 2 weeks, then 1 mg (2 mg a week total)
Route: Subcutaneous injection

Who: From the top-voted r/Retatrutide progress post, held for 12 months. People split the weekly dose because appetite control at 1 to 1.5 mg can fade by day 3 or 4. No trial tested split dosing.

Timing: Monday and Thursday is a common split.

Titration steps for Split dosing, twice weekly (community)
When	Dose	U-100 units (10 mg vial + 2 mL water)
Weeks 1 to 2	0.5 mg	10 units · 0.1 mL
Weeks 3 to 4	0.75 mg	15 units · 0.15 mL
Weeks 5 to 52	1 mg	20 units · 0.2 mL

Split dosing of the weekly total (guide)

Amount: 2 mg
How often: Weekly total split into 2 or 3 shots or every 2 to 3 days, e.g. 6 mg a week as 2 mg shots
Route: Subcutaneous injection

Who: A dosing guide's split schedule. No trial support.

Holding a mid-range dose (community)

Amount: 4 to 8 mg
How often: Once weekly, held at the dose that works
Route: Subcutaneous injection

Who: Community posters who stop climbing at 4 to 6 mg; others call 7 to 8 mg their best dose. Many never go to 12 mg.

Restart after a break (community)

Amount: 2 to 8 mg
How often: Once weekly: back to 2 mg, then 4, 6 and 8 mg in weekly steps
Route: Subcutaneous injection

Who: Community posters restarting after a few weeks off.

Titration steps for Restart after a break (community)
When	Dose	U-100 units (10 mg vial + 2 mL water)
Week 1	2 mg	40 units · 0.4 mL
Week 2	4 mg	80 units · 0.8 mL
Week 3	6 mg	120 units · 1.2 mL(2 draws)
Week 4	8 mg	160 units · 1.6 mL(2 draws)

Maintenance taper (community)

Amount: 4 to 8 mg
How often: Once weekly, stepping down over about 4 weeks: 8, 6, 5, then 4 mg
Route: Subcutaneous injection

Who: Community posters stepping down after reaching goal weight. Maintenance has not been studied.

Titration steps for Maintenance taper (community)
When	Dose	U-100 units (10 mg vial + 2 mL water)
Week 1	8 mg	160 units · 1.6 mL(2 draws)
Week 2	6 mg	120 units · 1.2 mL(2 draws)
Week 3	5 mg	100 units · 1 mL
Week 4	4 mg	80 units · 0.8 mL

Low-dose maintenance (community)

Amount: 0.5 to 2 mg
How often: Once weekly at 0.5, 1 or 2 mg
Route: Subcutaneous injection

Who: Community posters who settle at a low weekly dose after goal. Some report weight regain after tapering to 1 mg. Not studied.

Maintenance every 2 weeks (community)

Amount: 4 mg
How often: Every 2 weeks, e.g. 4 mg
Route: Subcutaneous injection

Who: Community posters debating the same dose every 2 weeks against a lower dose weekly. Some add a 2 mg boost shot on a 1 mg base when hunger returns. Not studied.

Maintenance, twice weekly (guide)

Amount: 1 mg
How often: 1 mg twice weekly (2 mg a week)
Route: Subcutaneous injection

Who: A dosing guide's maintenance suggestion after goal weight. No trial support.

General weekly range (guide)

Amount: 0.5 to 12 mg
How often: Once weekly
Route: Subcutaneous injection

Who: A guide's headline range across all phases, with 0.5 to 1 mg for early titration.

Doses shown are what sources report, labelled by origin. Not medical advice.

Community-reported amounts

The Retatrutide amounts people mention most on Reddit, by goal. Counts, not recommendations.

Retatrutide amounts reported on Reddit, by goal, with mention counts
Goal	Most reported amounts (mentions)
Weight loss	2 mg (283), 1 mg (222), 4 mg (145), 0.5 mg (108)
Goal not stated	5 mg (4), 0.5 mg (3), 2 mg (3), 10 mg (3)
Metabolic health	1 mg (3), 2 mg (3)

From 900 Reddit posts and comments, last mined Oct 23, 2026.

Retatrutide dosing chart by vial size

Units to draw for the doses sources cite most, at every vial size and water volume.

Retatrutide: concentration and U-100 syringe units for each vial size and water volume
Water	Strength	0.5 mgdose, units	1 mgdose, units	2 mgdose, units
5 mg vial
1 mLCompetitor guide	5 mg/mL	100.1 mL	200.2 mL	400.4 mL
2 mLCompetitor guide	2.5 mg/mL	200.2 mL	400.4 mL	800.8 mL
3 mLCompetitor guide	1.667 mg/mL	300.3 mL	600.6 mL	1201.2 mL2 draws
10 mg vial
1 mLCompetitor guide	10 mg/mL	50.05 mL	100.1 mL	200.2 mL
2 mLCompetitor guide	5 mg/mL	100.1 mL	200.2 mL	400.4 mL
3 mLCompetitor guide	3.333 mg/mL	150.15 mL	300.3 mL	600.6 mL
12 mg vial
1 mLCompetitor guide	12 mg/mL	4.20.042 mL	8.30.083 mL	16.70.167 mL
2 mLCompetitor guide	6 mg/mL	8.30.083 mL	16.70.167 mL	33.30.333 mL
3 mLCompetitor guide	4 mg/mL	12.50.125 mL	250.25 mL	500.5 mL
15 mg vial
1 mLCompetitor guide	15 mg/mL	3.30.033 mL	6.70.067 mL	13.30.133 mL
2 mLCompetitor guide	7.5 mg/mL	6.70.067 mL	13.30.133 mL	26.70.267 mL
3 mLCompetitor guide	5 mg/mL	100.1 mL	200.2 mL	400.4 mL
20 mg vial
1 mLCompetitor guide	20 mg/mL	2.50.025 mL	50.05 mL	100.1 mL
2 mLCompetitor guide	10 mg/mL	50.05 mL	100.1 mL	200.2 mL
3 mLCompetitor guide	6.667 mg/mL	7.50.075 mL	150.15 mL	300.3 mL
24 mg vial
1 mLCompetitor guide	24 mg/mL	2.10.021 mL	4.20.042 mL	8.30.083 mL
2 mLCompetitor guide	12 mg/mL	4.20.042 mL	8.30.083 mL	16.70.167 mL
2.4 mLCompetitor guide	10 mg/mL	50.05 mL	100.1 mL	200.2 mL
3 mLCompetitor guide	8 mg/mL	6.30.063 mL	12.50.125 mL	250.25 mL
30 mg vial
1 mLCompetitor guide	30 mg/mL	1.70.017 mL	3.30.033 mL	6.70.067 mL
2 mLCompetitor guide	15 mg/mL	3.30.033 mL	6.70.067 mL	13.30.133 mL
3 mLCompetitor guide	10 mg/mL	50.05 mL	100.1 mL	200.2 mL
40 mg vial
1 mLCompetitor guide	40 mg/mL	1.30.013 mL	2.50.025 mL	50.05 mL
2 mLCompetitor guide	20 mg/mL	2.50.025 mL	50.05 mL	100.1 mL
3 mLCompetitor guide	13.333 mg/mL	3.80.038 mL	7.50.075 mL	150.15 mL
50 mg vial
1 mLCompetitor guide	50 mg/mL	10.01 mL	20.02 mL	40.04 mL
2 mLCompetitor guide	25 mg/mL	20.02 mL	40.04 mL	80.08 mL
3 mLCompetitor guide	16.667 mg/mL	30.03 mL	60.06 mL	120.12 mL
60 mg vial
1 mLCompetitor guide	60 mg/mL	0.80.008 mLunder 1 unit	1.70.017 mL	3.30.033 mL
2 mLCompetitor guide	30 mg/mL	1.70.017 mL	3.30.033 mL	6.70.067 mL
3 mLCompetitor guide	20 mg/mL	2.50.025 mL	50.05 mL	100.1 mL

Units are on a U-100 insulin syringe (100 units = 1 mL). U-50 and U-30 barrels read the same units.Water volumes from

Doses shown are what sources report, labelled by origin. Not medical advice.

Calculate with this peptideYour vial, your water, your dose: Retatrutide in syringe units, with the math shown.

Mixing Retatrutide

Diluent: Bacteriostatic water

Water volumes sources use: 1 mL, 2 mL, 2.4 mL, 3 mL

Run the water down the inside wall of the vial, then swirl gently. Do not shake. At high doses people use a stronger mix, around 10 mg per mL, so one shot fits in a 1 mL syringe. One community poster mixes 20 mg with 3 mL on purpose, to make small dose steps easier to measure.

Retatrutide dosing questions

What is the starting dose of retatrutide?

The trials start at 2 mg once a week. In phase 2, starting at 2 mg instead of 4 mg cut stomach side effects and cost little weight loss. Community users usually start lower: 1 mg weekly is the most common start on r/Retatrutide, and some begin at 0.5 mg.

What is the retatrutide titration schedule?

Steps of 4 weeks. The phase 3 TRIUMPH ladder is reported as 2, 4, 6, 9, then 12 mg weekly, with targets of 4, 9 or 12 mg. Lilly confirms the 2 mg start and the 4-week steps. Many community users stop climbing once a mid-range dose works.

How much bacteriostatic water for a 10 mg retatrutide vial?

1 mL or 2 mL are the most common choices. 1 mL makes 10 mg per mL, which keeps higher doses small enough for one syringe. 2 mL makes 5 mg per mL, which is easier for small early doses. Use the calculator for the exact units.

What maintenance dose do people use on retatrutide?

It has not been studied. Community posters taper down to 0.5 to 2 mg weekly, or keep their dose and stretch it to every 2 weeks. Some report regain after tapering to 1 mg and add a small boost shot when hunger returns. Maintenance is one of the busiest topics on r/Retatrutide.

Why do people split their retatrutide dose?

At low doses like 1 to 1.5 mg, many users say appetite control fades by day 3 or 4 and hunger is back before the next shot. Splitting the weekly amount into two shots, often Monday and Thursday, evens that out. No trial has tested split dosing.

Do people cycle retatrutide?

Some do: 16 to 24 weeks on, 4 to 8 weeks off, tapering at the end. That pattern comes from community practice. No trial has tested cycling.

Sources for these doses

40 sources, each checked by date. Record updated Oct 23, 2026. Numbers are restated in our own words and labelled by where they came from.

Clinical study3

Preliminary results of retatrutide from TRIUMPH-1Lilly Medical · checked Oct 23, 2026
Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 TrialNew England Journal of Medicine · checked Oct 23, 2026
LY3437943, a novel triple agonist, in people with type 2 diabetes: a phase 1b trialThe Lancet · checked Oct 23, 2026

Competitor guide5

Retatrutide ProtocolPeptide Dosing Protocols · checked Oct 23, 2026
Retatrutide 5 mg vial dosage protocolPeptideDosages · checked Oct 23, 2026
Microdosing RetatrutideGLP3 Planner · checked Oct 23, 2026
Switching from tirzepatide to retatrutidePeptIQ · checked Oct 23, 2026

Community-reported32

Starting dose?r/Retatrutide · checked Oct 23, 2026
Given your height/initial weight, what was your starting dose?r/Retatrutide · checked Oct 23, 2026
First Dose / Startingr/Retatrutide · checked Oct 23, 2026
Starting Dose, Titration, and Side Effectsr/Retatrutide · checked Oct 23, 2026

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